The present invention relates to a method of and an arrangement for testing traffic routes in a telecommunication network.
With aid of the traffic route testing the grade of service of a telecommunication network can be checked and, provided the tests are performed in short inervals, the grade of service can be monitored. The test is done by setting up test calls between different points of the network. In the following description the grade of service is defined as the availability of the telecommunication network to a telephone subscriber, i.e. whether and after what period of time the subscriber, after having lifted the telephone handset, receives the dial tone; and whether and after what period of time after dialling, the ringing tone occurs; and whether the subscriber line loss for both directions of transmission lies within given values, whether the metering is correct, whether the release is done correctly.
As already mentioned, for the test of traffic routes, there are test calls set up by test apparatus to test stations provided with automatic answering devices and arranged within the different exchanges of the telecommunication network; and based on the results of the test calls, there is given evidence of the grade of service.
There are known different methods of and arrangements for testing traffic routes. In the easiest case, there is only tested whether and within what period of time a calling subscriber receives a dial tone. With more sophisticated methods, there is set up a complete connection with testing of both directions of transmission. The method of the present invention relates to a method of the last mentioned kind.
In "Ericsson-Review" 3/74 p. 80-87, there is described a traffic route tester setting up complete two-way connections. Said traffic route tester cooperates with a central processor as the controlling unit at a central point of the telecommunication network which processor controls traffic producing units in the exchanges via modems and switched lines or via through-connected lines which units set up test calls to other exchanges and transmit back the test results. The number of the simultaneously performable test calls within the telecommunication network is given by the number of the modems and/or through-connected lines available for the central unit. The number of test calls per time unit performable via a modem or a through-connected line is given by the time needed for setting up the call and transmitting back the result.
It is desirable to use a traffic route test not only for receiving statistical data concerning the grade of service of a telecommunication network, but also for monitoring the grade of service in an almost realtime manner. For this purpose, it would be necessary to have a rather large number of test calls per time unit between two exchanges in order to receive the desired realtime knowledge of the grade of service.
With the above described prior art traffic route tester, this would require a large number of modems with a corresponding charge to the exchange housing, the central unit wih unpaid test traffic or a large number of expensive through-connected lines and further, a very fast processor in the central unit due to the large data traffic.
It is, therefore, a primary object of the invention to provide a method of and an arrangement for testing traffic routes enabling the monitoring of the grade of service in a realtime manner without the aforementioned drawbacks.